1. Field of the Invention
The present invention relates to a method of forming barrier ribs in a plasma display panel (PDP) and, more particularly, to a method of forming barrier ribs with different depths.
2. Description of the Related Art
A plasma display panel (PDP) is a thin type display, usually has a large display area and a thin thickness. The luminescent principle of the PDP is the same as that of a fluorescent lamps. A vacuum glass trough is filled with inert gases. When a voltage is applied to the glass trough, some plasma will be occurred to radiate ultraviolet (UV) rays. After the fluorescent materials coated on the wall of the glass trough adsorb the UV rays, the fluorescent materials will radiate visible light including red light, green light and blue light. A plasma display can be viewed as a combination of hundreds of thousands of illuminating units, each illuminating unit has three subunits for radiating red light, green light and blue light, respectively. Images will be showed on the display by mixing these three primary colors.
As shown in FIG. 1, a conventional PDP 10 has a pair of glass substrates 12, 14 arranged in parallel and opposite to each other. A discharge space 16 is formed between the glass substrates 12, 14 and injected with inert gases, such as Ar, Xe or others. The upper glass substrate 12 has a plurality groups of transverse electrodes positioned in parallel. Each group of the transverse electrodes has a first and a second sustaining electrode 18, 20, and each sustaining electrode 18, 20 includes a transparent electrode 181, 201 and a bus electrode 182, 202. A dielectric layer 24 is further formed to cover these transverse electrodes, and a protection layer 26 is formed on the dielectric layer 24.
The lower glass substrate 14 has a plurality of barrier ribs 28 arranged in parallel and spaced a distance to each other for dividing the discharge space 16 into a plurality of group of sub-discharge spaces. Each group of the sub-discharge spaces includes a red discharge space 16R, a green discharge space 16G, and a blue discharge space 16B. Also, the lower glass substrate 14 has a plurality of lengthwise electrodes 22 positioned in parallel and between two adjacent barrier ribs 28 to serve as address electrodes. In addition, a red fluorescent layer 29R, a green fluorescent layer 29G, and a blue fluorescent layer 29B will be respectively coated on the lower glass substrate 14 and the sidewalls of the barrier ribs 28 within each red discharge space 16R, each green discharge space 16G, and each blue discharge space 16B.
When a voltage applied for driving these electrodes, the inert gases in the discharge space 16 will be discharged to produce UV rays. The UV rays further illuminate the fluorescent layers 29R, 29G, 29B to radiate visible lights including red light, green light and blue light. After the three primary colors are mixed at different ratios, various images are formed and transmitted through the upper glass substrate 12.
Considering the illuminant characteristics and the color purities of these three primary colors, some specific materials are used in the fluorescent layers 29R, 29G, 29B. For example, the red fluorescent layer 29R is formed by mixing Eu+3 and (Y,Gd)BO3, or Eu and Y2O3. The green fluorescent layer 29G is formed by mixing Mn and Zn2SiO4 or Mn and BaAl12O19. The blue fluorescent layer 29B is formed by mixing Eu+2 and BaMgAl14O23, or by Eu+2 and SrMg (SiO4)2. However, the fluorescent materials still have some disadvantages. For example, the lifetime of the blue fluorescent materials is too short, and the residual light produced by the green fluorescent materials exists too long. Therefore, the color temperature of the prior PDP 10 is too low, resulting in a poor quality of the display. In order to improve the quality, the widths of different discharge space are varied. The width of the blue discharge space is the biggest so as to increase the blue discharge space 16B to the maximum space. Thereby, the surface area of the blue fluorescent layer 29B can be increased to improve the property of blue light. Further, the color temperature of the PDP 10 can be increased to improve the quality of the display. However, the width of the red discharge space 16R may be reduced too much, and therefore, the processes of manufacturing the barrier ribs 28 and coating the red fluorescent layer 29R become more difficult. An alignment problem of the glass substrates 12, 14 is encountered because the width of the red discharge space 16R is small. In addition, the discharged gases may be flowed to the neighbor cells to cause a xe2x80x9ccross-talkxe2x80x9d phenomenon when the width of the red discharge space 16R is narrow. The electrical properties of the PDP 10 are then changed. In order to solve the problems described above, a method of forming the PDP with a high color temperature should be disclosed.
The present invention is a method of forming barrier ribs of a PDP with different depths of the discharge spaces.
The barrier ribs are formed on a substrate having a plurality of electrodes, a dielectric layer above the electrodes and the substrate, and a rib material layer on the dielectric layer. First, a first bottom pattern layer, a second bottom pattern layer and a third bottom pattern layer are formed above the rib material layer. These bottom pattern layers have the same width and are spaced apart to each other with the same distance. Second, a first middle pattern layer, a second middle pattern layer and a third middle pattern layer are respectively formed on the first bottom pattern layer, the second bottom pattern layer and the third bottom pattern layer. The left sidewalls of the first middle pattern layer and the first bottom pattern layer are aligned. The right sidewalls of the second middle pattern layer and the second bottom pattern layer are aligned. Both of the right and left sidewalls of the third middle pattern layer and the third bottom pattern layer are respectively aligned. Then, a first top pattern layer and a second top pattern layer are respectively formed on the first middle pattern layer and the third middle pattern layer. The left sidewalls of the first top pattern layer and the first middle pattern layer are aligned. The right sidewalls of the second top pattern layer and the third middle pattern layer are aligned. Next, a sandblasting process is performed by using the bottom pattern layers, the middle pattern layers, and the top pattern layers as a mask, so that parts of the rib material layer are removed to expose parts of the dielectric layer. Finally, the barrier ribs are formed after removing the bottom pattern layers, the middle pattern layers, and the top pattern layers.
Accordingly, it is a principle object of the invention to provide the barrier ribs with different depths.
It is another object of the invention to adjust the surface areas of fluorescent materials coated on different discharge spaces.
Yet another object of the invention is to adjust the depths of different discharge spaces.
It is a further object of the invention to increase the color temperature of the PDP.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.